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David Howells642fb4d2006-01-06 00:11:41 -08001/* file-nommu.c: no-MMU version of ramfs
2 *
3 * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/module.h>
13#include <linux/fs.h>
Dimitri Gorokhovik131612d2006-12-29 16:48:24 -080014#include <linux/mm.h>
David Howells642fb4d2006-01-06 00:11:41 -080015#include <linux/pagemap.h>
16#include <linux/highmem.h>
17#include <linux/init.h>
18#include <linux/string.h>
David Howells642fb4d2006-01-06 00:11:41 -080019#include <linux/backing-dev.h>
20#include <linux/ramfs.h>
David Howells642fb4d2006-01-06 00:11:41 -080021#include <linux/pagevec.h>
22#include <linux/mman.h>
Catalin Marinas5c805362009-07-29 15:04:11 -070023#include <linux/sched.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090024#include <linux/slab.h>
David Howells642fb4d2006-01-06 00:11:41 -080025
26#include <asm/uaccess.h>
27#include "internal.h"
28
29static int ramfs_nommu_setattr(struct dentry *, struct iattr *);
30
Christoph Hellwigf5e54d62006-06-28 04:26:44 -070031const struct address_space_operations ramfs_aops = {
David Howells642fb4d2006-01-06 00:11:41 -080032 .readpage = simple_readpage,
Nick Piggin800d15a2007-10-16 01:25:03 -070033 .write_begin = simple_write_begin,
34 .write_end = simple_write_end,
Ken Chen46626292007-02-10 01:43:17 -080035 .set_page_dirty = __set_page_dirty_no_writeback,
David Howells642fb4d2006-01-06 00:11:41 -080036};
37
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -080038const struct file_operations ramfs_file_operations = {
David Howells642fb4d2006-01-06 00:11:41 -080039 .mmap = ramfs_nommu_mmap,
40 .get_unmapped_area = ramfs_nommu_get_unmapped_area,
Badari Pulavarty543ade12006-09-30 23:28:48 -070041 .read = do_sync_read,
42 .aio_read = generic_file_aio_read,
43 .write = do_sync_write,
44 .aio_write = generic_file_aio_write,
David Howells642fb4d2006-01-06 00:11:41 -080045 .fsync = simple_sync_file,
Jens Axboe5ffc4ef2007-06-01 11:49:19 +020046 .splice_read = generic_file_splice_read,
Octavian Purdila8b3d3562008-07-04 09:33:33 +020047 .splice_write = generic_file_splice_write,
David Howells642fb4d2006-01-06 00:11:41 -080048 .llseek = generic_file_llseek,
49};
50
Arjan van de Venc5ef1c42007-02-12 00:55:40 -080051const struct inode_operations ramfs_file_inode_operations = {
David Howells642fb4d2006-01-06 00:11:41 -080052 .setattr = ramfs_nommu_setattr,
53 .getattr = simple_getattr,
54};
55
56/*****************************************************************************/
57/*
58 * add a contiguous set of pages into a ramfs inode when it's truncated from
59 * size 0 on the assumption that it's going to be used for an mmap of shared
60 * memory
61 */
Nick Piggin4b19de62008-10-02 14:50:16 -070062int ramfs_nommu_expand_for_mapping(struct inode *inode, size_t newsize)
David Howells642fb4d2006-01-06 00:11:41 -080063{
Mike Frysinger0f67b0b2009-12-17 15:27:14 -080064 unsigned long npages, xpages, loop;
David Howells642fb4d2006-01-06 00:11:41 -080065 struct page *pages;
66 unsigned order;
67 void *data;
68 int ret;
69
70 /* make various checks */
71 order = get_order(newsize);
72 if (unlikely(order >= MAX_ORDER))
npiggin@suse.dec08d3b02009-08-21 02:35:06 +100073 return -EFBIG;
David Howells642fb4d2006-01-06 00:11:41 -080074
npiggin@suse.dec08d3b02009-08-21 02:35:06 +100075 ret = inode_newsize_ok(inode, newsize);
76 if (ret)
77 return ret;
David Howells642fb4d2006-01-06 00:11:41 -080078
79 i_size_write(inode, newsize);
80
81 /* allocate enough contiguous pages to be able to satisfy the
82 * request */
83 pages = alloc_pages(mapping_gfp_mask(inode->i_mapping), order);
84 if (!pages)
85 return -ENOMEM;
86
87 /* split the high-order page into an array of single pages */
88 xpages = 1UL << order;
89 npages = (newsize + PAGE_SIZE - 1) >> PAGE_SHIFT;
90
Nick Piggin84097512006-03-22 00:08:34 -080091 split_page(pages, order);
David Howells642fb4d2006-01-06 00:11:41 -080092
93 /* trim off any pages we don't actually require */
94 for (loop = npages; loop < xpages; loop++)
95 __free_page(pages + loop);
96
97 /* clear the memory we allocated */
98 newsize = PAGE_SIZE * npages;
99 data = page_address(pages);
100 memset(data, 0, newsize);
101
102 /* attach all the pages to the inode's address space */
David Howells642fb4d2006-01-06 00:11:41 -0800103 for (loop = 0; loop < npages; loop++) {
104 struct page *page = pages + loop;
105
Johannes Weiner26789582009-03-31 15:23:29 -0700106 ret = add_to_page_cache_lru(page, inode->i_mapping, loop,
107 GFP_KERNEL);
David Howells642fb4d2006-01-06 00:11:41 -0800108 if (ret < 0)
109 goto add_error;
110
Enrik Berkhan020fe222009-03-13 13:51:56 -0700111 /* prevent the page from being discarded on memory pressure */
112 SetPageDirty(page);
113
David Howells642fb4d2006-01-06 00:11:41 -0800114 unlock_page(page);
115 }
116
David Howells642fb4d2006-01-06 00:11:41 -0800117 return 0;
118
npiggin@suse.dec08d3b02009-08-21 02:35:06 +1000119add_error:
Johannes Weiner26789582009-03-31 15:23:29 -0700120 while (loop < npages)
121 __free_page(pages + loop++);
David Howells642fb4d2006-01-06 00:11:41 -0800122 return ret;
123}
124
125/*****************************************************************************/
126/*
David Howells642fb4d2006-01-06 00:11:41 -0800127 *
128 */
129static int ramfs_nommu_resize(struct inode *inode, loff_t newsize, loff_t size)
130{
131 int ret;
132
133 /* assume a truncate from zero size is going to be for the purposes of
134 * shared mmap */
135 if (size == 0) {
136 if (unlikely(newsize >> 32))
137 return -EFBIG;
138
139 return ramfs_nommu_expand_for_mapping(inode, newsize);
140 }
141
142 /* check that a decrease in size doesn't cut off any shared mappings */
143 if (newsize < size) {
David Howells7e660872010-01-15 17:01:39 -0800144 ret = nommu_shrink_inode_mappings(inode, size, newsize);
David Howells642fb4d2006-01-06 00:11:41 -0800145 if (ret < 0)
146 return ret;
147 }
148
Bryan Wu3f0a6762007-05-31 11:31:55 +0800149 ret = vmtruncate(inode, newsize);
David Howells642fb4d2006-01-06 00:11:41 -0800150
151 return ret;
152}
153
154/*****************************************************************************/
155/*
156 * handle a change of attributes
157 * - we're specifically interested in a change of size
158 */
159static int ramfs_nommu_setattr(struct dentry *dentry, struct iattr *ia)
160{
161 struct inode *inode = dentry->d_inode;
162 unsigned int old_ia_valid = ia->ia_valid;
163 int ret = 0;
164
Bryan Wu85f60382007-06-05 11:02:01 +0800165 /* POSIX UID/GID verification for setting inode attributes */
166 ret = inode_change_ok(inode, ia);
167 if (ret)
168 return ret;
169
David Howells642fb4d2006-01-06 00:11:41 -0800170 /* pick out size-changing events */
171 if (ia->ia_valid & ATTR_SIZE) {
172 loff_t size = i_size_read(inode);
173 if (ia->ia_size != size) {
174 ret = ramfs_nommu_resize(inode, ia->ia_size, size);
175 if (ret < 0 || ia->ia_valid == ATTR_SIZE)
176 goto out;
177 } else {
178 /* we skipped the truncate but must still update
179 * timestamps
180 */
181 ia->ia_valid |= ATTR_MTIME|ATTR_CTIME;
182 }
183 }
184
185 ret = inode_setattr(inode, ia);
186 out:
187 ia->ia_valid = old_ia_valid;
188 return ret;
189}
190
191/*****************************************************************************/
192/*
193 * try to determine where a shared mapping can be made
194 * - we require that:
195 * - the pages to be mapped must exist
196 * - the pages be physically contiguous in sequence
197 */
198unsigned long ramfs_nommu_get_unmapped_area(struct file *file,
199 unsigned long addr, unsigned long len,
200 unsigned long pgoff, unsigned long flags)
201{
202 unsigned long maxpages, lpages, nr, loop, ret;
Josef Sipeka57c4d62006-12-08 02:37:32 -0800203 struct inode *inode = file->f_path.dentry->d_inode;
David Howells642fb4d2006-01-06 00:11:41 -0800204 struct page **pages = NULL, **ptr, *page;
205 loff_t isize;
206
207 if (!(flags & MAP_SHARED))
208 return addr;
209
210 /* the mapping mustn't extend beyond the EOF */
211 lpages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
212 isize = i_size_read(inode);
213
214 ret = -EINVAL;
215 maxpages = (isize + PAGE_SIZE - 1) >> PAGE_SHIFT;
216 if (pgoff >= maxpages)
217 goto out;
218
219 if (maxpages - pgoff < lpages)
220 goto out;
221
222 /* gang-find the pages */
223 ret = -ENOMEM;
224 pages = kzalloc(lpages * sizeof(struct page *), GFP_KERNEL);
225 if (!pages)
David Howells0e8f9892009-01-08 12:04:46 +0000226 goto out_free;
David Howells642fb4d2006-01-06 00:11:41 -0800227
228 nr = find_get_pages(inode->i_mapping, pgoff, lpages, pages);
229 if (nr != lpages)
David Howells0e8f9892009-01-08 12:04:46 +0000230 goto out_free_pages; /* leave if some pages were missing */
David Howells642fb4d2006-01-06 00:11:41 -0800231
232 /* check the pages for physical adjacency */
233 ptr = pages;
234 page = *ptr++;
235 page++;
236 for (loop = lpages; loop > 1; loop--)
237 if (*ptr++ != page++)
David Howells0e8f9892009-01-08 12:04:46 +0000238 goto out_free_pages;
David Howells642fb4d2006-01-06 00:11:41 -0800239
240 /* okay - all conditions fulfilled */
241 ret = (unsigned long) page_address(pages[0]);
242
David Howells0e8f9892009-01-08 12:04:46 +0000243out_free_pages:
244 ptr = pages;
245 for (loop = nr; loop > 0; loop--)
246 put_page(*ptr++);
247out_free:
248 kfree(pages);
249out:
David Howells642fb4d2006-01-06 00:11:41 -0800250 return ret;
251}
252
253/*****************************************************************************/
254/*
David Howells21ff8212006-07-10 04:44:52 -0700255 * set up a mapping for shared memory segments
David Howells642fb4d2006-01-06 00:11:41 -0800256 */
257int ramfs_nommu_mmap(struct file *file, struct vm_area_struct *vma)
258{
David Howells2e92a3b2007-07-31 00:37:24 -0700259 if (!(vma->vm_flags & VM_SHARED))
260 return -ENOSYS;
261
262 file_accessed(file);
263 vma->vm_ops = &generic_file_vm_ops;
264 return 0;
David Howells642fb4d2006-01-06 00:11:41 -0800265}